Legalism permeated the medieval Christian church and the impact of that legalism on medieval institutions is an uncontested, if somewhat under-explored phenomenon. The institution of matrimony received a definition and character at the hands of the canon lawyers which it would continue to posses for centuries to come. If their efforts to regulate medieval marital practice were less than completely successful, the canonists did not fail to influence Western attitudes towards marriage and human sexuality.

This essay deals with canonical doctrine about sexual relations in marriage in the period between the twelfth and the mid-fourteenth centuries – the era in which scientific jurisprudence came of age. Its specific focus is the concept of conjugal debt, that is, the notion that both husband and wife had a duty to perform sexually at the request of their mate.

Originally derived from Paul, 1 Corinthians 7.3-6, this equal opportunity concept formed a cornerstone for canonical discussions of marital sex. The lawyers attempted to assimilate this ideal along with other more restrictive but no less authoritatice pronouncements, into the developing laws of the Church. An ingenious and eclectic doctrine resulted in which the canonists relied frequently, though not exclusively, on two distinguished authorities, Paul and Augustine.